Respuesta :

[tex]f(x)=3x^2-6x+6\\\\f(x)=3(x^2-2x)+6\\\\f(x)=3(\underbrace{x^2-2x+1}-1)+6\\\\ f(x)=3[(x-1)^2-1]+6\\\\f(x)=3(x-1)^2-3+6\\\\f(x)=3(x-1)^2+3[/tex]

RELAXING NOICE
Relax